Author: Dan Marsden
MDL-60347 core: debugsmtp should be a developer only setting.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=b48c1715dfd6b776a495f43ff1fc5858981a2d01
http://github.com/moodle/moodle/commit/b48c1715dfd6b776a495f43ff1fc5858981a2d01
+ 3.6 en [configdebugsmtp,core_admin]